Carol,

I consider myself a serious student of certain forms of American traditional music which I don't think will help you much. The only thing I can suggest for European circus music is maybe check classical music. I know for American music to find serious recordings of the music of Stephen Foster or other nineteenth century popular songs I look in the classical section.

I saw your post earlier and I agree it must be even more difficult to find discussions of instrumental music. What is the unpopular instrument that you play?